ABSTRACT Suicide is a major public health concern ? it is the 10th leading cause of death and number one cause of injury related death in the United States (US). Suicide rates have risen over 25% in the last 15 years. In parallel, the nation is struggling with an opioid epidemic. Opioid prescribing, heroin use, and opioid related overdose deaths have risen substantially. Approximately 15% of all suicide deaths are due to drug overdose, and prescription opioids specifically, are commonly used among people who attempt suicide. Health systems across the country have made decisions to tackle both of these public health crises ? implementing policies to dramatically reduce opioid prescribing as well as clinical processes within the Zero Suicide model to improve suicide prevention for their patients. The parent award for this supplement is focused on evaluation of Zero Suicide implementation, including fidelity to each of these clinical processes and suicide outcomes, across 6 large, diverse Mental Health Research Network-affiliated Learning Healthcare Systems providing healthcare for over 9 million individuals each year. Given the overlap, significant reductions in opioid prescribing as part of newly implemented policies should lead to a reduction in the availability of opioids. These reductions may result in a public-health level means reduction approach to reduce suicide. Means reduction is among the interventions recommended within Zero Suicide. The concurrent implementation of these new opioid prescribing policies in the context of implementation of Zero Suicide allows the opportunity to evaluate how changes in opioid prescribing impacts suicide outcomes in health care. This supplement project seeks to accomplish three specific aims: 1) Evaluate changes in opioid prescribing patterns during the period of NZSM implementation across health systems, 2) Investigate whether changes in opioid prescribing patterns reduce suicide attempt and mortality, and 3) Investigate whether changes in opioid prescribing patterns reduce opioid- related suicide attempt and mortality poisonings. Overall, we propose to use an Interrupted Time Series Design, consistent with the parent award, to measure changes in prescribing patterns and suicide outcomes.